| Various methods which discharge sediments in dam reservoirs have recently been implemented. Highly turbid water is run off to downstream regardless of any methods， but the effects on stream ecosystem are poorly understood. Experimental studies have shown that turbid water has negative effects on benthic periphyton. However， many of the studies have examined at slower velocity than at the actually observed in effluent floods. Thus， we examined effects of velocity and turbid water(suspended solids) on benthic periphyton， using experimental channels which can provide high velocity(0.5-4.0m/s). Inorganic matter in periphyton increased with suspended solids. On the other hand， effects of suspended solids on chlorophyll a depended on velocity. Although chl. a did not vary with suspended solids in low velocity(0.5m/s)， that increased with suspended solids in high velocity(4.0m/s)， suggersting that inorganic layer formed on the surface of periphyton may prevent abrasion of algae. This study indicates that effects of sediment discharge on benthic periphyton vary with contents of suspended solids and velocity. |
